A basic understanding of the main parts of a home HVAC system is useful for any homeowner. Knowing what a part is and what it does makes it easier to discuss basic maintenance or even major repairs or equipment replacement with your HVAC contractor.

A typical home HVAC system in the Conroe area includes both heating and air conditioning. Most newer homes and many older homes were built with central heating and cooling systems, where the furnace and air conditioner share a few of the same parts in order to save space and reduce the up-front cost of the systems.

Parts Shared by the Heating and A/C Systems

  • Air handling unit – Central heating and A/C systems usually share the same air handling equipment. A fan run by an electric motor is installed in the furnace housing where it blows air across the heat exchanger or evaporator coil and into the ductwork for distribution throughout the house.
  • Ductwork – Central heating and cooling systems usually share the same ductwork. The supply ducts distribute conditioned air throughout the house and return ducts carry air back to the air handling unit. Ducts can be installed in attics, crawl spaces, behind walls or above dropped ceilings. For optimum energy efficiency, ducts should be well sealed and insulated anywhere they run outside the home’s conditioned space.
  • Vents – Each room in the house usually has a supply vent that brings conditioned into the room from the ductwork. A rectangular grille covers the vent opening and lets air move without allowing small animals, children or other large objects to enter the ductwork. Return vents may be installed in every room, or there may be a common return vent in a hallway serving several rooms. It’s important to keep airflow unobstructed between the supply and return vents to keep the home HVAC system in proper balance.
  • Thermostat – The temperature inside the home is controlled by the thermostat, which can be a modern programmable model or an older manually operated model. In heating mode, the thermostat sends a signal to the furnace to come on whenever the inside temperature drops below the set level, and in cooling mode the thermostat tells the air conditioner to turn on whenever the inside temperature rises above the set level.
  • Air filter – The furnace filter keeps dust, pet hair and other debris from entering the ductwork, where it can reduce indoor air quality and interfere with efficient operation of the heating and cooling equipment. You should change the air filter regularly for best system performance.

Heating System Parts

  • Furnace – The furnace is contained in a metal housing which is usually placed in a utility room or closet inside the house. Sometimes furnaces are installed in the attic or garage. Furnaces that burn natural gas are the most common in the Conroe area, although some furnaces burn propane or fuel oil, and other heating systems rely on electric resistance heating rather than fossil fuels. The supply and return ducts are connected to the furnace housing, and the air handling equipment is installed inside the furnace housing.
  • Heat exchanger – The heat exchanger transfers heat from the burner to the air inside the ductwork, where the air handler blows it throughout the house. It’s critical that the heat exchanger be in good condition so that combustion gases don’t leak from the burner into the home via cracks or holes caused by corrosion.

Air Conditioning Parts

  • Evaporator coil – A refrigerant runs in a closed loop inside the air conditioning system between the indoor equipment and the outdoor unit. The evaporator coil is located inside the furnace housing adjacent to the air handling equipment. As the refrigerant flows through the evaporator coil, it absorbs heat from the air blowing across the coil. The resulting cool air is distributed throughout the house via the ductwork.
  • Condenser coil – The compressor and condenser coil are located in the air conditioning system’s outdoor unit. The heat-laden refrigerant from inside the house flows through the condenser coil, which, similar to a car’s radiator, radiates the heat to the outdoors. The refrigerant is then compressed and returned to the indoor unit where it will continue the cooling cycle. For efficient operation, it’s critical that both the indoor and outdoor coils be kept free of dust, leaves or other debris that might reduce heat flow across them.

Call us at Conroe Air with any questions you have about your home HVAC system in Montgomery County and surrounding areas.